MUCH better audio.
Definitely enhanced bass. I eventually installed alpha5 and am currently using it. The audio did change. I have a pretty good new audio system in my car, and the empeg used to sound pretty well before a5, as well. I don't know yet how much better it sounds to me, but its definitely not worse, and I did have to decrease bass in the equalizer by two points, too.
However, I am now wondering how is this possible. What was changed? For some oversimplifying reasons, I thought the audio quality would ultimately depend on the hardware, meaning that the empeg player sw was already "perfect" from the audio quality standpoint...